import { useCallback, useEffect, useMemo, useState } from 'react';

import { sortStoryOptionsByPriority } from '../data/stateFunctions';
import { annotateStoryOptionsWithGoalAffordance } from '../services/storyEngine/goalDirector';
import type { GoalStackState, StoryMoment } from '../types';

const OPTION_PAGE_SIZE = 3;

export function useStoryOptions(
  currentStory: StoryMoment | null,
  goalStack?: GoalStackState | null,
) {
  const [optionWindowStart, setOptionWindowStart] = useState(0);

  const activeOptionPool = useMemo(() => {
    if (!currentStory) {
      return [];
    }

    return sortStoryOptionsByPriority(
      annotateStoryOptionsWithGoalAffordance(
        currentStory.options,
        goalStack,
      ),
    );
  }, [currentStory, goalStack]);

  const optionPoolSignature = useMemo(
    () =>
      activeOptionPool
        .map((option) =>
          [
            option.functionId,
            option.actionText,
            option.text ?? '',
            option.goalAffordance?.goalId ?? '',
            option.goalAffordance?.relation ?? '',
          ].join('::'),
        )
        .join('||'),
    [activeOptionPool],
  );

  useEffect(() => {
    setOptionWindowStart(0);
  }, [currentStory, optionPoolSignature]);

  const displayedOptions = useMemo(
    () => {
      const windowOptions = activeOptionPool.slice(
        optionWindowStart,
        optionWindowStart + OPTION_PAGE_SIZE,
      );
      if (
        windowOptions.some(
          (option) => option.goalAffordance?.relation === 'advance',
        )
      ) {
        return windowOptions;
      }

      const pinnedAdvanceOption =
        activeOptionPool.find(
          (option) => option.goalAffordance?.relation === 'advance',
        ) ?? null;
      if (!pinnedAdvanceOption) {
        return windowOptions;
      }

      return [
        pinnedAdvanceOption,
        ...windowOptions
          .filter(
            (option) =>
              !(
                option.functionId === pinnedAdvanceOption.functionId
                && option.actionText === pinnedAdvanceOption.actionText
              ),
          )
          .slice(0, OPTION_PAGE_SIZE - 1),
      ];
    },
    [activeOptionPool, optionWindowStart],
  );

  const canRefreshOptions = activeOptionPool.length > OPTION_PAGE_SIZE;

  const handleRefreshOptions = useCallback(() => {
    if (activeOptionPool.length <= OPTION_PAGE_SIZE) return;

    const nextStart = optionWindowStart + OPTION_PAGE_SIZE;
    if (nextStart < activeOptionPool.length) {
      setOptionWindowStart(nextStart);
      return;
    }

    setOptionWindowStart(0);
  }, [activeOptionPool.length, optionWindowStart]);

  const resetStoryOptions = useCallback(() => {
    setOptionWindowStart(0);
  }, []);

  return {
    activeOptionPool,
    displayedOptions,
    optionWindowStart,
    canRefreshOptions,
    handleRefreshOptions,
    resetStoryOptions,
  };
}